In recent years, researches have been made to reduce reflected light from the liquid crystal surface of a television, a mobile phone or the like by providing an antireflection structure having a fine concave-convex structure, the cycle of which is controlled to be the wavelength of visible light or less, to the surface of the article. In addition, as one of such methods, a method for manufacturing an antireflection article by forming a fine concave-convex structure through the anodizing of the surface of aluminum, and transferring the fine concave-convex structure to a molding material, such as a resin have been adopted. Reported examples of the fine concave-convex structure formed through anodizing include a structure made up of a plurality of fine pores having a substantially circular cone shape, a substantially circular truncated cone shape or the like.
In a case in which the surface of aluminum is anodized so as to produce a stamper, and the surface is transferred so as to manufacture an article, since the shape of the surface of the stamper is mirrored at the surface of a transfer target as it is, the regularity or shape of the surface of the stamper is important in terms of the antireflection function.
Therefore, it is found that it is preferable to contain an extremely small number of secondary phase particles, which may form a defect in an oxide film, in aluminum, and a fine concave-convex structure having a little defect can be obtained by applying pure aluminum with a small number of elements to be added and impurities, which serve as the origin of the secondary phase particles (for example, refer to Paragraph [0025] in PTL 1).